Infant cribs must be designed and constructed to provide a safe environment for the infant and to meet various government safety standards. Such safety standards have become increasingly more stringent over the years as concern about child safety has risen in public awareness. Standards exist for example with respect to the spacing between the slats of crib sides, and the mesh sizes acceptable for the sides of portable folding cribs or playpens. Standards also exist as to acceptable materials and their strength and flammability characteristics for crib construction. A relatively new standard has been propounded in Canada and has been proposed in the United States and other countries which requires that the mattress of a crib be able to withstand an upward force beneath the mattress of a minimum of 224 pounds such as could occur by an older child playing beneath the crib or from a dog moving below the crib or from some other inadvertent upward force applied to the bottom of the mattress of its support. Such an unintended upward force could dislocate the mattress and could eject the infant from the crib or otherwise cause harm to the child.